Most studies on pesticides and Parkinson's disease (PD) focused on occupational exposure in farmers. Whether non-occupational exposure is associated with PD has been little explored. We investigated the association between agricultural characteristics and PD incidence in a French nationwide ecologic study. We hypothesized that persons living in regions with agricultural activities involving more intensive pesticide use would be at higher risk. We identified incident PD cases from French National Health Insurance databases (2010-2012). The proportion of land dedicated to 18 types of agricultural activities was defined at the canton of residence level. We examined the association between agricultural activities and PD age/sex-standardized incidence ratios using multivariable multilevel Poisson regression adjusted for smoking, deprivation index, density of neurologists, and rurality (proportion of agricultural land); we used a false discovery rate approach to correct for multiple comparisons and compute q-values. We also compared incidence in clusters of cantons with similar agricultural characteristics (k-means algorithm). We identified 69,010 incident PD cases. Rurality was associated with higher PD incidence (p < 0.001). Cantons with higher density of vineyards displayed the strongest association (RRtop/bottom quartile = 1.102, 95% CI = 1.049-1.158; q-trend = 0.040). This association was similar in men, women, and non-farmers, stronger in older than younger persons, and present in all French regions. Persons living in the cluster with greatest vineyards density had 8.5% (4.4-12.6%) higher PD incidence (p < 0.001). In France, vineyards rank among the crops that require most intense pesticide use. Regions with greater presence of vineyards are characterized by higher PD risk; non-professional pesticides exposure is a possible explanation.

Background: pesticides have been associated with Parkinson's disease (PD), but there are few data on important exposure characteristics such as dose-effect relations. It is unknown whether associations depend on clinical PD subtypes.
Objectives: we examined quantitative aspects of occupational pesticide exposure associated with PD and investigated whether associations were similar across PD subtypes.
Methods: as part of a French population-based case-control study including men enrolled in the health insurance plan for farmers and agricultural workers, cases with clinically confirmed PD were identified through antiparkinsonian drug claims. Two controls were matched to each case. Using a comprehensive occupational questionnaire, we computed indicators for different dimensions of exposure (duration, cumulative exposure, intensity). We used conditional logistic regression to compute odds ratios (ORs) and 95% confidence intervals (CI) among exposed male farmers (133 cases, 298 controls). We examined the relation between pesticides and PD subtypes (tremor dominant/non-tremor dominant) using polytomous logistic regression.
Results: there appeared to be a stronger association with intensity than duration of pesticide exposure based on separate models and a synergistic interaction between duration and intensity (p-interaction = 0.04). High intensity exposure to insecticides was positively associated with PD among those with low intensity exposure to fungicides and vice versa, suggesting independent effects. Pesticide exposure in farms specialized in vineyards was associated with PD (OR = 2.56; 95% CI: 1.31, 4.98). The association with intensity of pesticide use was stronger, although not significantly (p-heterogeneity = 0.60), for tremor dominant (p--trend < 0.01) than for non-tremor dominant PD (p--trend = 0.24).
Conclusions: this study helps to better characterize different aspects of pesticide exposure associated with PD, and shows a significant association of pesticides with tremor dominant PD in men, the most typical PD presentation.

Background: vitamin D is thought to contribute to brain health, but it is unclear whether low vitamin D levels are associated with increased incidence of Parkinson's disease (PD). Using ultraviolet B (UV-B) as a surrogate for vitamin D levels, we conducted a nationwide ecologic study in France in order to examine the association of UV-B with PD incidence.
Methods: we used French national drug claims databases to identify PD cases using a validated algorithm. UV-B data from the solar radiation database were derived from satellite images. We estimated PD incidence (2010 2012) at the canton level (small administrative French unit) and used multilevel Poisson regression to examine its association with UV-B (2005 annual average), after adjustment for age, sex, deprivation index, density of neurologists, smoking, proportion of agricultural land, and vitamin D supplementation.
Results: analyses are based on 69,010 incident PD patients. The association between UV-B and PD incidence was quadratic (P<0.001) and modified by age (P<0.001). Below 70y, incidence was higher in the bottom quintile (relative risk, RRQ1:45-49y=1.18, 95% CI=1.08 1.29) compared with the middle UV-B quintile, and lower in the top quintile (RRQ5:45-49y=0.85 [0.77 0.94]). An opposite pattern was observed in older subjects (RRQ1:85-89y=0.92 [0.89 0.96]; RRQ5:85-89y=1.06 [1.02 1.11]). Analysis based on continuous UV-B yielded similar conclusions.
Conclusions: in this nationwide study, there was an age-dependent quadratic association between UV-B and PD incidence. This study suggests that reasonable UV-B exposure is associated with lower PD risk in younger persons and that future studies should examine dose-response relations and take age into account.

Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's. PD is considered a multifactorial disorder that results, in most cases, from the combined effects of multiple risk and protective factors, including genetic and environmental ones. This review discusses some of the methodological challenges involved in assessing the descriptive, prognostic and etiological epidemiological studies of PD, and summarizes their main findings.

Background and purpose: the association of farming with motor neuron disease (MND) is unclear, with conflicting studies. We performed a French nationwide study of the association of farming with MND incidence, and compared findings with those for Parkinson's disease (PD), which has been shown to be more frequent in farmers.
Methods: we used the French national health insurance and hospital discharge databases to identify MND/PD incident cases. The Mutualité Sociale Agricole (MSA) guarantees health insurance for farmers and agricultural workers. We compared the incidence of MND (2010 2014) and PD (2011 2012) in MSA farmers, MSA workers and non-MSA affiliates, and estimated relative risks (RRs) and 95% confidence intervals (CIs). Probabilistic sensitivity analyses were used for external smoking adjustment.
Results: analyses relied on 8931 MND (MSA, 9%) and 45 409 PD (MSA,11%) cases. There was a trend towards higher MND incidence in MSA farmers compared with non-MSA affiliates (RR,1.08; 95% CI,0.99 1.18) and MSA workers (RR, 1.13; 95% CI, 0.97 1.31) that strengthened after smoking adjustment (if associated with MND). PD incidence was higher in MSA farmers than non-MSA affiliates (RR, 1.13; 95% CI, 1.08 1.17) and MSA workers (RR, 1.10; 95% CI, 1.02 1.18); this association remained after smoking adjustment (RR, 1.09; 95% CI, 1.05 1.14).
Conclusions: this French nationwide study suggested an association between farming and MND, and confirmed higher PD incidence in farmers in France, a country with high pesticide use.